Picture transmission



Mrch 25, 1930.

C. W. HANSELL PICTURE TRANSMISSION 3 Sheets-Sheet 1 Filed Aug. 13, 1927a w n w mnm 50E? 5 m5 INVENTOR CLARENCE W. NISELL Patented Mar. 25, 1930a This invention relates to picture transmission, and includes methodswhich may or may not involve the intermediateuse of electrical energy.

' It is an object of my invention to make possible the, transmission ofradiant energy, m a curved path, and this I do by employin .a conductorcomposed of transparent su stance having'a large criticalrefractionangle, such as quartz, andliending the conductor to followfliedesired path.

- It is a further object of m invention to control the concentration 0energization, that is, to make possible a change in intensity as well asa change in direction of radiant energy during its transmission, andthis I do by suitably varying the cross section of the quartz conductor.

It is a further object of my invention to :0 make a conductor forradiant energy which shall be relatively flexible, which I do bybuildingup a cable out of so many relatively fine strands of quartz thatthe resultant cable is sufiicientl flexible for the purpose desired.,Such 9. ca le is not merely suitable for con-' ducting radiant energybut also for transmitting and reproducing radiant energy of varyinintensities, for-each strand 1. 1%"- lated m the adjacent strands, andthere'- ac fore the "intensit ""doesnotaverage. In effeet, then, the cale becomes a icture transfer cable, which may be apphed to .a wide rangeof uses. For example, such a cable may be used for tra'nsferring'theirjeading. of instruments from inaccessib to accessible locations, asthe reading of a gasoline gage .from the gas tank to the dashboard of anautomobile. Or it may be used by surgeons for examining inaccessibleinternal parts of a the body, or by mechanics to examine in- "visibleinteriors of complicated castings, or in war time as a flexible penscope'I shall more particularly describe the use of such a cable inconnection with picture I45 transmission over reat distances through theintermediate use 0 electrical waves. In such 3 picture transmissionitiscustomary to have movable means to scan the picture to be reproduced,and the resultant picture cons sts of the of a large a I r Irrcruna'ramsmssron cell has proved troublesome, an

number of such ."uurrsb .sr TEs, PATENT OFFICE CLARENCE 'W. EANSELL, OFROCKY POINT, NEW YOiK, ASSIGNOB 1'0 RADIO CORPORA- 'lION OF AMERICA, .5.CORPORATION OF DELAWARE Application filed Augult 1a, 1927. Serial No.212,503.

scanning movements. To transfer the light from the scanning means to a(photo-electric for this purpose my invention is especially a plicable.

The time for transmission 0 a complete picture depends upon the totalnumber of scanning movements necessary to integrate the picture, and toreduce the necessary number of scanning movements is a furtherob-- jectof my invention. This I propose to so do by utilizing a multiplescanning means,

and a plurality of photo-electric cells arranged to control a multiplextransmitter. For simultaneously scanning a pluralit of ad acent pomts inpicture transfer cab e is 05 especially useful, or at each end thestrands m be separated and an sitioned as desired,

the -flexibility of t e'intermediate cable i I the picture is moved, thecable permits of picture' transmission from closely points to se aratedphoto-sensitive es s located 'out o the normal direct path of the nor. a

i -To increase the speed of intelligence trans-'1. mission eflorts arebeing made to employ facsimile reproduction instead of tele aphic code.For this purpose in multip e scan- 59 .nin device is well applicale,'for the ends of t e cable strands mayibe arranged to simul tivesecrecy of signalling, fononl stations 05 properly 'uippe will be ableto ecode the j transmitte si als. Furthermore, b V the use of my specialcable the relative or or of permits movement of the scanning means,or-if the scanning means are stationary and j ad'acent I -'radiantenergy, a very convenient man- 75,

the scanning linesmay be mixed up as desired at th' transmitter, andonly i the r a 14; :"f'f i Q sensation of heat.

very similarly to the transmitting means except that in place of thephoto-electric cells there are light sources independently responsive tothe electrical signals received over the various signal channels, andlight from each of these sources is impressed upon the separated ends ofthe strands of a quartz cable. The other end of the cable is formed intoa multiple printing means which is placed in transverse juxtaposition toa light sensitive surface on which the facsimile is printed.

The invention is described more in detail in the following specificationwhich is accompanied by drawingsin which Figure 1 shows a conductor oftransparent material characterized by a largecritical angle ofrefraction;

Figure 2 indicates a cable composed of a large number of strands of suchmaterial;

Figure 3 represents the scanning end. of a cable used for facsimiletransmission;

Figure 4 is a cross section of such a cable having a flexible core; IFigure 5 is a cross section of a cable as in Fi re 4 wherein each strandis itself a cable;

igure 6 shows how the terminae may be formed into convenient shapes ofdesired cross section area;

Figure 7 schematically indicates both a scanning arrangement at atransmitter, and

a rinting arrangement at a receiver;

igure 8 is a wiring diagram for a. trans,- mitter;

Figure 9 is a wiring diagram for a receiver;

Figure 10 is a transmitter for frequency modulation; and

Figure 11 is a receiver for frequency modulated signals.

Referring to Figure 1 it is seen that radiant energy from a source 2 isimpressed on a transversely cut end of a conductor 6. I This conductoris preferably made of fused quartz but may be made of glass, though withless satisfaction, or of any transparent substance havin a largecritical angle of refraction, so

are refracted, somewhat as indicated by t e dotted lines in the figure.If the curvature is not made too shar the radiant energy is entirelyconfined-an is emitted at the other end 8. Ba-

" w diant heat energy is transferred as well as lighlfiiher anexperimentally, the remote end of sue a rod ma be used to ignite papereven though the con uctor is quite cool along its surface, and may beheld without any The radiant energy in such a conductor is mixed up andaveraged out at the far end. If it is desired to transmit radiant energyof varying intensities and to reproduce equivalent energies at anotherpoint a cable may be formed, as is indicated in Figure 2. If the cableis used for picture transfer it is obvious that the fineness of detailwill depend upon the cross section area of theindividual strands. Thecable may be twisted, but for picture transfer the strands should keeptheir relative position. Such a cable consti! tutes a simple means forlooking around 'cor-' ners and complicated curves, and is very usefulwhen circumstances are such that reflecting prisms or mirrors cannotwell be used. hasalready been mentioned, it may be used for transferringthe readings of gages, :or for any number of inspection pur ses.

I intend more particularly to emp oy the cable for picture and facsimiletransmission. Fi re 3 indicates a cable intended for multipTie scanningwhere a five channel multiplex signal system is to be used. There is ascannin head 14 within which there are clampe the ends of five parts ofthe quartz cable 16. a

For increasing flexibility a core of more flexible material may be usedas indicated in Figure 4, the quartz conductors 18 being wound upon acore 20. Also each of the conductors 18 may itself be a cable com osedof a lar e number of fine quartz threa s which may e arrangedindiscriminately, as indicated by the cables 22 formed upon the core 20in Figure 5.

In Figure 6 there is shown a conductor the end 10 of which has beenformed into a desirable shape for scanning a line of a picture, whilethe other end 12 has been enlarged to pzrmit the light picked up at theend 10 to impressed uKon a greater area of a photobe ex osed to afluctuating light source, whilethe light is then greatly intensified andreproduced at as small an area as desired for the photographic printing1 Referring to Figure 7 t ere is a drum 30 on which a picture 32 isfixed. The drum ma be transparent, and illuminated from wit in. Thecable 16 terminates at one end in a scanning head 14 which isreciprocated longtudinally of the drum 30 by a reciprocating carria e34. Mechanism is provided so that at eac reciprocation of the carriage34 the drum 30 is rotated a distance equivalent to the spacin betweenthe lines of type, in the case of acsimile transmission, but in the'case of picture transmission the rotation is equivalentto the effectivewidth of the scannin head 14..

It is t ought not necessary to describe the mechanical details, nor themethod of synchronizing the transmitter and the receiver The cable 16leads to an enclosure 36, within which there are located hoto-electriccells and associated circuits whrch are further described in connectionwith Figures 8 and 10.

In Figure 8 the five ends of the quartz cable, numbered 22, are suitablyenlarged and conyeniently separated, and each is placed m uxtapositionto a photo-electric cell 40.

The cell 1s in series with a resistance 42, and

thence, by way of the conductor 44, with a source of constantelectromotive force C. As the resistance of the cell is alteredaccording to the light sensitization impressed thereon the otential at apoint betweenthe cell 40 and t e' constant resistance 42 fluctuates, andthis potential fluctutation is im pressed on the grid of an electronemission tube 46. There are five such tubes, and the anode circuits ofthese tubes are provided with rela; coils 48 which influence armatures50 to ma e and break the circuits of the alternating current sources 52,which each have difi'erent frequencies, indicated by f f f,, f., and f,,each representing a separate sign channel. The alternating currentsources may be miniature rotary converters, or rotary frequencychangersenergized from a single alternating current line.

The complex wave *representing the sum at any instant of the waves offrequenc f,, f,, etc., 1s transferred over a line 54, w 'ch may a longland line leadin from the transmltter to the receiver, in t e case of awire transmission, or from an urban oflice to a suburban transmissionstation, in the case of radio transmission.

' At the radio transmitting station there is a source of carrierfrequency 56, which preferably 1s crystal-contro1led by a crystal 58.The carrler energy is supplied symmetrically to a push-pull modulator60, as shown in the wiring diagram, and in consequence of this thecarrier 1s ehminated from the output 62, and only the two side bands andthe on al modulating frequencies are produced. i filter 64 is arrangedpreferab y as a high pass filter with cut-off at the carrier frequency,so that the modulating frequencies'and the lower side band areehminated. The upger side band is amplified b a power amp i er 66, theoutput'from w ich is radiated by means of an antenna system 68, theexact form of which will depend on considerations The transmitter hasbeen described in such as frequency and directivity.

simple form, and it is clear that the,use of relays such as 48, 50 isprobably only for facsimile transmission, because such relays do notreproduce the varying shades of light characteristic of a picture, teither make or break, according as the picture is dark or light. In thecase 0 picture transmission it is preferably toobtain modulation ratherthan make or break,and to do this we may amplify the energy output fromeach tube 46 and use it to modulate ener of frequencies f etc., or wemay use t e simple direct in ulation sch'eme shown in the left handportion of Figure 10. The modulation of these land line fre uencies willthen be reproduced in the si e band at is, they finally transmitted fromthe antenna sysy tem 68.

Fi ure 9 indicates a receiving circuit in simp e form. The signals arepicked up on an antenna and are transferred through a coupling 72 to arectifying tube 74. A heterod mug current is supplied from a a source 76, which preferably is'crystal controlled by a crystal 78, and combinedwith the incoming wave by means of the coupling 72 and the rectifyingtube 74. The heterodyning fre uency may equal the carrier frequenc at te transmitter, in which case'the beat requencies will equal thefrequencies f f etc. To so do is convenient, but not necessary, for ifthe heterodyne frequency is different the beat frequencies will be f 1etc., which will differ from each at or by the same amountsas the etc. I

The complex low frequency wave may be amplified by an amplifier 'andthen, conveyed over a land line 82 to a reproducing means locatedwherever convenient. In the case of wire transmission the line will bethe line 82, connected to the line 54 in Figure 8. At the end of theline there may be an amlifier 84, the output of which is coupled toEltersf86 each of whichis adjustedtoselect oneof the frequencies f fetc. The output of the filters 86 may be amplified by amplifiers 88, andthen used-eitherindirectly,

frequencies )3, f2,

or directly, as shown, to ener 'ze 1i ht sources 90. These are exposedto e en 22 of a picture transfer cable such as was used at thtransmitting station.

is reciprocated by a carriage'34 across a photo sensitive surface 32mounted upon a drum 30. 1

It is clear that if the reciprocations of carriage 34 at the transmitterand at the receiver occur even relatively crudely in synchronism thefacsimile will be reproduced with suflicient fidelity. i r

Another arrangement for transmission is indicated in Figure 10, in whichit is seen that the ends 22 of the strands of a light cable areositioned before light sensitive cells 40, as in igure 8. The cells,instead of being connected in series with a direct current source, arein series with alternating current 70 is coup sources 52,havingfrequencies f ,f ,etc. Each cell being essentially a variable resistancethis arrangement results directly in amplitude modulation of thealternating energies. The modulated signal ener ies are preferablyamplified in the am lif ying tubes 102, the output from which is coupledby means of the transformers 104 to a common bus 106 to which a landline 54 is connected.

As so far described this arrangement provides a complex signalling wavethe com onent energies of which are modulated rat er than completely cutoff, and the land line 54 may be connected to a carrier suppressionmodulator such as was described in connection with Figure 8. However, insome cases it may be desirable to use frequency modulation, rather thanamplitude modulation, and in such a case the signal energy from the landline 54 in either Figure 8 or 10 is led to a frequency Wobbler.

This has been shown in Figure 10, wherein the oscillator 110 has forpart of the reactance of its resonant circuit 112 the radio frequencywinding of a magnetic Wobbler 114. The land line 54 is connected to thesaturation winding of the Wobbler. The frequency F; of the frequencymodulated oscillator 110 may be a transmission frequency, or it may be:an intermediate frequency which is then used to modulate energy of ahigher frequency F generated in a constant frequency oscil ator 116. Theenergy from this oscillator is coupled symmetrically through radiofrequency condensers to a push-pull modulator stage 120. The frequencymodulated energy of intermediate frequency is used to modulate highfrequency energy, and of the two resulting side bands the filter 64selects one, which may then be amplified in a power amplifier 66 andradiated from an antenna system 68.- The side band is constant inamplitude because the intermediate frequency energy is constant i1}amlplitude, while-the mean'frequency F ility of the high frequencyoscillator 116, which preferably is crystal controlled.

A receiver for frequency modulated si nals has-been shown in Figure 11,in whic the energy gicked up by the antenna system e to the inputcircuit of a combining tube 74, to which there is also coupled anoscillator 76. The local oscillator ma supply ener of frequency F inwhic case there wil result a beat frequency equal to thetransmissionintermediate frequency F but this is not an essentialcondition. The intermediate frequency energy is amplified i. anamplifier 122, the output from which is coupled to an analyzing circuit124. This is a resonant circuit the fre uency of which is adjusted tolie to one si e of the operating range of intermediate frequencysupplied to is quite uniform because of the sta-' energy is directedtowards the ends 22 of a light cable 16, as has already been describedin connection with Figure 7.

The systems described are relativel secret because an interceptingreceiver wi l have to exactly duplicate the actual receiver employed.Even with'make and break signalling, as is shown in Figure 8, ordinaryreceivers will be unable to multiplex and unable to decode theequivalent dots and dashes of a single scannin line. The secrecy may befurther increase by rearranging the relative order of the scanning linesin a similar manner at both the transmitter and the receiver.

It is clear that the arran ement disclosed herein may be used on lanlines as well as with radio systems. Any convenient number of signalchannels may be employed. Any type of multiplex transmitter and receivermay be utilized, whether employing frequency or amplitude'modulation,and I shall therefore use the term modulation broadly, intending it toinclude both.

I claim: 7 1. In combination, a source of radian energy, a devicelocated out of the normal direct path of said radiant energy forresponse thereto, and means to convey said energy from the source to thedevice com rising a flexible quartz conductor ca able 0 being movedrelatively thereto, sai conductor having transversely cut ends locatedin juxtaposition to the source and the device.

2. In combination, a surface to be scanned, scannin means including oneend of a relatively exible strand of quartz, means provide by saidflexibility for permitting movement 0 said scannin means relative tosaid surface, hoto-electrlc means responsive to the light intensity ofsaid surface, and means comprising the aforesaid strand of quartz toconvey' the light from the surface to the photo-electric means.

3. In combination, a surface to be scanned, scanning means including oneendof a relatively flexible quartz cable having a plurality of strandsof quartz for scanning a redetermined number of unit areas of saisurface, means provided by said flexibility of Cable for permittingrelative motion between said' scanning means and said surface,photo-electric means responsive to the light intensity of said quartzcable to convey t tively flexible quartz cable having a plurality ofstrands of quartz, means to move said scanning means over said surface,a plurality of photo-electric cells responsive to the light intensity ofthe portions of said surface scanned by the strands of said cable, andmeans comprising the aforesaid cable to convey the light from saidsurface portions to the cells.

5. In combination, a surface to be scanned, scanning means including oneend of a relatively flexible quartz cable having a pluralityof strandsof quartz, means to move said scanning means over said surface, aplurality of separated photo-electric cells res onsive to the lightintensity of the portions 0 said surface scanned by the strands of saidcable, and means comprising the aforesaid cable to convey the light fromsaid surface portions to the cells, the strands of said cable beingspread apart at one end and positioned separately adjacent the cells.

' 6 A picture transmission system comprising multiple scanning means, aplurality of photo-electric cells, a plurality of quartz conductors forconveying light from the multiple scanning means to the ce Is, amultiplex transmitter having a plurality of signal channels,

. ling on the several channels inaccordance and means controlled by thecells for signalwith the light intensities impressed on the multiplescanning means.

I. A facsimile transmission system comprising a plurality ofphoto-electric cells, a plurality of strands of quartzone set of ends ofwhich are superposed transversely of a hne of print for scanning theline in a single scanning movementand the other ends of which areconveniently'separated and increased in area for cooperation withtheplurality of photo-electric cells, and amultiplex transmission systemthe several signal channels of which are independently controlled bysaid cells: a

8. In combination, a hght sensitive surface to be rinted, printing meansincluding one end 0 a relativel flexible strand of quartz,

end 0 means provided y the flexibility of said quartz strand for permittng movement of said printing means over sa1d surface, a lu m1- noussource responsive to received electrical signals, and means comprisinthe aforesaid strand of quartz to convey ght from the ,source to theprinting means. I 9. In combination, a light sensitive surface to berinted, printing means including one Fa relatively flexible quartz cablehaving a plurality of strands of quartz for prlnting a plurality of unitareas on sa1d surface simultaneously, means to move the printing meansover and surface and means pro- Y vided by the flexibility of said cablefor permitting said movement of thesaid printing means relative to saidsurface, a luminous source responsive to received electrical sig-' nals,and means comprising the aforesaid 7o quartz cable to convey light fromthe source to the surface.

10. In combination, a light sensitive surface to be printed, multipleprinting means including one end of a relatively flexible quartz cablehaving a plurality of strands of quartz,.means to move said printingmeans over said surface, a plurality of luminous sources eachindependently, responsive to re ceived electrical signals, and meanscoinprising the .aforesaid cable to independently convey light from eachof said sources to the printing means. i

11. In combination, a light sensitive surface to be printed, arelatively flexible quartz 35 cable formed of a plurality of strandsseparated at one end, printing means including the other ends of thestrands of the quartz cable arranged in superposition, means to movesaid printing means over said surface, a plurality of separated luminoussources each independently responsive to received electrical signals,and means comprising the strands of the aforesaid quartz cable to conveylight from each of said sources to the printing means, the separatedends of the strands of said cable being positioned adjacent theseparated luminous sources. 7

12. In a picture transmission'system, a reproducer comprising aplurality of variable light sources, a plurality of strands of quartzone set of ends of which are positioned transversely of the direction ofprinting and the other ends of which are conveniently sep-' arated andincreased in area for cooperation with the lurality of variable lightsources, and a mu tiplex receiving system for independently controllingthe light emission from each of said sources. 13. In a facsimiletransmission system, a reproducer comprising a plurality of variab elight sources, a plurality ofstrands 6f quartz one set of ends of whichare superposed transversely of the direction of a line of print forphoto printing the line in a single passage and the other ends of whichare conveniently separated and increased in area for cooperation withthe plurality of variable light sources, and a multiplex receivin systemfor independently controlling the lig t emission fronieach of saidsources. 1.4. In combination, a surface to be scanned, a lightresponsive relay, and a flexible member of greater refractive boundarythan the surrounding medium for conveying impressions of the lightintensity on said surface to said relay, and means provided by theflexibility of said member for permittin relative motions between saidsurface an member for vely causing renpon es 13c.

from said relay proportionate to the successive light intensitiesforming the entirety of said surface.

15. The combination of a source of light, a relatively long flexiblelight conveying element having a sharp light confining boundarythroughout its length for distributing light from said source, a surfaceres onsive to light and means rovided by the exibility of said elementor permittin movement thereof relative to said sur ace for causing saidlight to influence the same, and means for effecting relative movementof the said cable to said surface.

16. The combination of a source of light, a plurality of flexibleconducting rods adjacent said source for pickin up the light therefromand distributing t e same at a point remote therefrom in a predeterminedmanner, a light sensitive record surface at the end of said rods remotefrom said source, and means provided by said flexibility of rods and theplurality thereof for respectively permitting relative motion betweensaid rods and said surface and influencin said light sensitive surfaceat a plurality 0 points simultaneously.

17. A system for increasing the speed of picture transmission bymultiplexing which includes means for simultaneously scanning a pluralitof adjacent points located transversely o the direction of seaming, aplurality of elongated flexible light conveyin elements for conveyingthe light from eac of said points along predetermined aths, aphoto-electric element at the end 0 each of said light conveyingelements, means for simultaneously transmitting a plurality of indeendent signals over carriers of different etpuencies, and means providedby said photo-e ectric elements for simultaneously modulating each ofsaid carriers in accordance with the intensity of li ht and shadowconveyed through each of sai light conducting elements for influencingsaid cells.

CLARENCE W. HANSELL.

